Deep Brain Stimulation: Surgical Process

Transcription

1 Deep Brain Stimulation: Surgical Process Kia Shahlaie, MD, PhD Assistant Professor Bronte Endowed Chair in Epilepsy Research Director of Functional Neurosurgery Minimally Invasive Neurosurgery Department of Neurological Surgery University of California, Davis

2 Outline Brief history Basal ganglia review Physiology (rate model) Parkinson s disease DBS Procedure Step 1: direct, indirect, physiological targeting Step 2: pulse generator implantation Postop care and outcomes Programming Risks and benefits of DBS

3 Irving Cooper ( ) Born in Atlantic City, NJ Son of a salesman Worked his way through school BA, MD, MS, PhD, NSG residency Faculty at NYU, then NYMC Pioneer in functional neurosurgery Anterior choroidal artery ligation Cooper IS: Parkinsonism: Its Medical and Surgical Therapy. Springfield, Ill: Charles C Thomas, 1961

4 What do the basal ganglia do? Scale Movement amplitude and velocity Focus Movement select specific muscles suppress antagonist muscles H Y P E R D I R E C T I N D I R E C T D I R E C T Rate Model: Direct: Facilitate wanted movements Indirect: Inhibit unwanted movements

5 Rate Model THALAMOCORTEX STRIATUM BASAL GANGLIA GPi

6 Rate model explains kinetic disorders Hypokinetic disorders: Parkinson s disease Hyperkinetic disorders: Dystonia, hemiballism, HD Delong, TINS 1990:13,

7 Focused excitation/surround inhibition model of BG function I N D I R E C T D I R E C T H Y P E R D I R E C T Mink Prog Neurobiol 1996 Nambu Neurosci Res 2002

8 Rate model provided the rationale for basal ganglia surgery in PD Loss of DA input to striatum Direct pathway is underactive Indirect pathway is overactive NET: Excess inhibition of thalamocortical relay Nuclei that are overactive in PD STN (driving the GPi) GPi (inhibiting the thalamus) X X

9 GPi and STN are overactive in PD Loss of dopaminergic activity results in disinhibition of the STN and GPi STN GPi normal: PD:

10 DBS Surgery for PD Indications Clear diagnosis of idiopathic PD Continued good motor response to dopamine Motor fluctuations and dyskinesias from meds Independent ambulation in best on state Contraindications Dementia Age > 80years (?) Poor function in best on state Poor MD/patient relationship Unilateral/bilateral Cognitive status, laterality of symptoms

11 Goals of DBS surgery Primum non nocere! elective operation Accurate implantation Location, location, location Awake, stereotactic surgery 1) Indirect targeting 2) Direct targeting 3) Physiological targeting Microelectrode recording/mapping Test stimulation Adjustable, reversible system Zona incerta STN Red SNc nucleus SNr CN III CN III nerve roots nerve roots Oculomotor nucleus Medial of of CN III III lemniscal pathway AXIAL PLANE Brain Orientation

12 DBS Surgery Steps 1) Indirect targeting 2) Direct targeting 3) Physiological targeting

13 Indirect Targeting Develop 3D coordinate system Define AC, PC, and 3 midline points 3D map with MCP at 0,0,0mm

14 Indirect Targeting Select target based on atlas data Vectors STN X (lateral) 12mm Y (ant/post) 3mm Z (sup/inf) 4mm

15 Direct Targeting Revise based on direct visualization, internal landmarks Along anterior edge of red nucleus on axial 3mm lateral to edge of red nucleus 2mm below superior edge of red nucleus

16 Direct Targeting Select entry point and trajectory Entry Avoid cortical veins Enter crest of gyrus Burr hole location Trajectory Avoid sulci Avoid ventricle Avoid subependyma Avoid major parenchymal vessels

17 Day of surgery Head frame placed using local anesthesia Localizer box used for CT provides fiducials Merge with MRI plan Patient placed in comfortable position, then sedated

18 DBS Surgery Prepped and draped. Incision and burr hole placed. Stereotactic head frame set to proper coordinates mer with patient awake

19 Physiological Targeting: mer Subthalamic nucleus (STN) Globus pallidus internus (GPi) Goal: Dorsolateral motor territory of STN leg area is medial arm area is lateral Goal: Posterior motor territory of GPi leg area is dorsal/medial arm area is ventral/lateral

20 Physiological Targeting: Test Stimulation Subthalamic nucleus (STN) Globus pallidus internus (GPi)

21 Interpreting STN Test Stimulation Error Structures Side effect Too lateral IC: CBT IC: CST FEF fibers Dysarthria Tonic contractions Contra gaze dev Too medial Too posterior Too anterior CN3 Red nucleus Limbic STN Med Lemnisc IC: CST IC: CBT Hypothalam Diplopia Paresthesia, flush Personality Parasthesia Tonic contractions Dysarthria Flushing Zona incerta STN Red SNc nucleus SNr CN III CN III nerve roots nerve roots Oculomotor nucleus Medial of of CN III III lemniscal pathway

22 Intraoperative Imaging: ict Standard OR, equipment, surgical technique; awake surgery with mer

23 Post implantation MRI Subthalamic nucleus (STN) Globus pallidus internus (GPi)

24 Hospital stay: 1 night

25 Stimulator Implantation Outpatient surgery (same day discharge, general anesthesia)

26 Clinic follow up for programming Physician programmer monopolar C+/1 Bipolar 0 /1+ Patient programmer Contacts/monopolar/bipolar Voltage Frequency Pulsewidth

27 Benefits of DBS for PD ~ 30% improvement in motor scores ~ 40% improvement in ADL scores ~ 50% reduction in PD medication needs DBS is typically as effective as best dopamine response Likely to improve: Tremor Rigidity (tightness) Bradykinesia (slowness) Dystonia Dyskinesia* Unlikely to improve: Gait instability / falls Freezing of gait Speech Swallow Cognitive deficits

28 Risks of DBS surgery Infection: 5 10% ICH/hemorrhage: 2 4% Neurological deficit: <1% from Starr PA and Silay C, 2008